An IP address is a unique number that identifies a site or a hosting server on the world-wide web, so in the event that you have a dedicated IP, it'll be used solely by your websites and shall not be shared with others as it happens with shared web hosting accounts. Provided you have your own web server, you will have a dedicated IP, but you may require extra ones for various purposes. If you have a web-based store, for example, you'll need an SSL certificate for it, to make certain that the payment info that your customers submit shall be encrypted and secure. The same is valid in the event that you have a login form of some sort and you want the usernames and the passwords which visitors enter to be protected. The SSL certificate requires a dedicated IP address, which needs to be different from the one that you already have on the hosting server. You may also need a separate IP for an application such as a VoIP server, or if you need a slightly better efficiency for a particular site, which may influence its position in search engine results.